1. Field of the Invention
The present invention relates to exit devices, of the type used to rapidly and reliably open exit doors and allow people to exit public buildings in the event of a fire, panic situation or other emergency. More particularly, the present invention relates to electrically illuminated exit devices.
2. Description of Related Art
An “exit device” is a lock mechanism operated from the inside of an outward swing door through the use of a crossbar, push bar or push rail actuator, that is designed to open an exit door, allowing exit without prior knowledge of how the lock operates, whenever a horizontal force is applied to the actuator. Exit devices are typically required by fire or building codes and are used in public buildings where many people may be gathered, to provide rapid, safe and easy egress in case of emergency.
Exit devices ensure that an exit door is free to operate from the inside of the locked area, yet they allow the exit door to remain locked to prevent unauthorized entry from the outside.
Although exit devices have been highly successful in performing the function for which they were designed, deaths in public building fires continue to occur. Some deaths can be traced to the inability of those within the building to quickly identify all the building exit doors when smoke from the fire obscures required exit signage. Such signage is typically located close to the ceiling of public rooms, which permits it to be seen over the heads of those within the room. However, this location is the first to become obscured when smoke and heated air from a fire rise to the ceiling in the room.
There remains a need to improve exit signage and to directly and rapidly signal to the public the location of each exit door and the location of the actuator for each exit door, particularly in low light or smoke-obscured conditions that accompany a fire.
Conventional illumination devices, which might meet this need, such as incandescent bulbs, are bulky, fragile, provide non-uniform illumination and produce excessive heat, all of which makes them unsuitable for installation in an exit device. An exit device is subject to repeated impact as the door is operated, so any illuminator located therein must be extremely rugged. The illuminator must not produce heat which could potentially burn a user touching metal components of the exit device, or which might present a fire hazard when the exit device is installed on a wooden door. The illuminator must be long lasting to minimize maintenance costs, yet it must reliably illuminate in an emergency situation.